Adjustable seat frame

ABSTRACT

The invention relates to a seat frame for fitting to the running gear ( 15 ) of a wheelchair or pushchair, comprising a backrest ( 1 ), a seating surface ( 2 ) and feet support ( 3 ). The aim of the invention is to produce a seat frame which is particularly flexible and may be adjusted to various sizes. Said aim is achieved, whereby long recesses, in particular grooves ( 5 ), are arranged running longitudinally along both sides of the seating surface ( 2 ), for housing fixing elements. Preferably, long recesses, in particular grooves ( 5 ), are also arranged running longitudinally along both sides of the backrest ( 1 ), for housing fixing elements.

[0001] The present invention relates to a seat shell, designed inparticular for attachment to the chassis of a wheelchair or a stroller,having a backrest, a seat, and a footrest.

[0002] A plurality of such seat shells, permanently or detachablyconnected to a chassis, are known from the related art.

[0003] Thus, for example, U.S. Pat. No. 4,039,223 describes a wheelchairin which the footrest and the backrest are lockable in differentpivoting positions with respect to the seat.

[0004] European Patent Application 911 008 A2 of the Applicant shows aseat shell in which the backrest and the footrest freely pivot withrespect to the seat. Furthermore, the backrest is supported by avertical section of the wheelchair frame. The seat is held pivotably ona slide guide, which allows the seat to move forward, as well as topivot upwardly. A tensioning device draws the seat back to its surfaceinto its flat position where it rests on the wheelchair frame, thebackrest assuming the angled position with respect to the seat. Anadditional tensioning device prestresses the footrest over its entirepivoting range with respect to the seat so that it is also pivoted intothe angled position. The movable seat arrangement described in thisApplication offers an extremely innovative and advantageous device fordisabled patients suffering from spastic extension spasms. In suchpatients spastic muscle spasms cause uncontrolled extension movements.Prior to the introduction of the object of the aforementioned EuropeanPatent Application, these extension movements were absorbed by rigidwheelchairs. The device described in the aforementioned European PatentApplication allows the components of the wheelchair to follow theextension movements in a controlled manner by applying an elasticrestoring force. The pivot axes of the components of this seat shell aresituated at the physiologically optimum pivot points, i.e., the backrestis rotatably linked to the seat in the area of the hip joint, and thefootrest is rotatably linked to the seat in the area of the knee joint.

[0005] Finally, an additional seat shell for attachment to the chassisof a wheelchair is known from German Patent 199 30 103 C1. This seatshell has adopted the pivotable connection between the backrest and thefootrest, which in this case is attached to the chassis of thewheelchair. In addition, it has thorax truss pads, i.e., support pillowsfor the thorax, which are attached to the back seat so they are able topivot transversely.

[0006] The object of the present invention is to provide a seat shellwhich is particularly flexible and which is adjustable to differentsizes.

[0007] This object is achieved according to the present invention inthat on both sides of the seat oblong recesses, grooves in particular,running in their longitudinal direction, are situated for receivingfastening elements.

[0008] Oblong recesses, grooves in particular, for receiving fasteningelements are preferably also situated on both sides of the backrestrunning in their longitudinal direction.

[0009] The oblong recesses running in the longitudinal direction arehereinafter referred to as grooves, although it is possible, of course,to provide other recesses such as elongate holes or grooves forreceiving the fastening elements.

[0010] The grooves running in the longitudinal direction of the seatallow the displacement of the fastening elements with which the footrestor the backrest are mounted on the seat, for example. Thus, the seatshell may be continuously adjusted to the size of the patientaccommodated in it. This continuous adjustability is helpful inparticular for young patients, i.e., children and adolescents, who arestill growing. An almost arbitrary adjustment for size is possible dueto the fastening elements which are essentially displaceable in thelongitudinal direction of the seat and/or the backrest.

[0011] According to a preferred embodiment of the present invention, ametallic extruded profile is mounted on each side of the seat. Thebackrest may also be provided with a metallic extruded profile on eachside. As a rule, such extruded profiles are made of aluminum and have anessentially square cross section. Each side face of the extruded profileis, as a rule, provided with a continuous groove which has undercuts.Fastening elements, which positively engage the undercuts, may beinserted into the groove. Furthermore, an additional oblong recess,i.e., a central channel or a central bore running in the longitudinaldirection, is situated within the extruded profile.

[0012] Such extruded profiles are mass produced for erecting temporarystructures, at trade fairs for example. They are available fairlycost-effectively. Due to the mounting of the extruded profile on bothsides of the plate forming the seat or on the plate forming thebackrest, a plurality of grooves running in the longitudinal directionmay be defined on both sides of the particular plates in a simplemanner; fastening elements may be attached in those grooves.

[0013] Of course, after the wheelchair's assembly including theattachment of all fastening elements, the plates and the extrudedprofiles are to be furnished with padding and a, for the most part,textile protective cover in order to ensure that the surfaces supportingthe body of the patient sitting in the seat shell are soft and cannotinjure the patient.

[0014] Holding elements, using which the backrest is articulatedlyconnected to the chassis of the wheelchair, may be mounted in thelongitudinal grooves of the backrest. In a preferred embodiment, aholding element, pivotably connected to a vertical frame of the chassis,is situated approximately in the upper third of the backrest. Such aholding element is mounted on each of the two extruded profiles whichare situated laterally of the backrest. The pivotability in thepreferred embodiment ensures that the backrest is freely pivotable withrespect to the surface of the seat shell against an elastic restoringforce and, when a spastically disabled person is seated in the seatshell, may follow the extension movements due to spastic spasms.

[0015] Bar-shaped fastening elements may be inserted into the bore inthe center of the extruded profiles. This makes it possible that thelongitudinal bores of the extruded profiles on the backrest may receive,for example, support bars for a headrest. Fastening elements may besituated in the longitudinal bores of the extruded profiles on the seat;these elements mount and lock adjustable lateral support surfaces to theseat shell which are in contact with the buttocks and the thighs of thepatient sitting in the seat.

[0016] Of course, the longitudinal grooves on the seat and on thebackrest may receive joining elements on both sides of these components,the joining elements connecting the backrest with the seat. In a rigidwheelchair, these joining elements may be simple, rigid butt plateswhich are mounted on the backrest and the seat on both sides of theseat. In the preferred embodiment mentioned, in which the backrest, withrespect to the seat, is freely pivotable in a certain angle range, thejoining elements have an articulated design.

[0017] Of course, joining elements which support the footrest may alsobe mounted on the longitudinal grooves of the seat.

[0018] The articulated joining elements are, as a rule, composed of twobase plates. The first base plate is mounted in the longitudinal grooveon one side of the seat using two fastening screws. A corresponding baseplate is situated in the longitudinal groove on the opposite side of theseat. A similar base plate is mounted on each side of the backrest inthe longitudinal groove being situated there. At their free ends the twobase plates each have a bore, a common rotational axis passing throughthe bores.

[0019] The joining elements for the footrest have a similar design, sucha joining element being mounted on each side of the seat in the frontarea of the longitudinal groove situated there. A narrow base plate, towhich the footrest is rigidly attached, is pivotably attached to thisbase plate. In a preferred embodiment, the footrest may be designed sothat its length is telescopically adjustable.

[0020] The joining elements are preferably mounted in the longitudinalgrooves using attachment screws. The heads of the attachment screws areintroduced into the longitudinal grooves positively engaged and engagethe undercuts situated there. Alternatively, the screws may be screwedfrom the outside into a female thread which is mounted in a slidingblock within the longitudinal groove. The sliding block is drawn againstthe undercut in the groove of the extruded profile by tightening thesescrews.

[0021] In particular in the plate-shaped joining elements, theattachment screws are preferably introduced into elongate holes whichrun transversely to the grooves. This makes a displacement of thejoining elements in the transverse direction to the groove on the seatand/or on the backrest possible.

[0022] The preferred embodiment of the seat shell is arbitrarilyadaptable in a wide range. The fastening elements may be displaced inthe grooves or in the longitudinal bores on the sides of the seat or thebackrest. In addition, the fastening screws in the long holes on thejoining elements may be displaced transversely to the grooves.

[0023] The seat shell according to the present invention is preferablymounted on a chassis which itself has an adjustable design. The chassismay follow the size adjustment of the seat shell in this way. As a rule,the chassis of a wheelchair includes a horizontal support componentwhich carries the seat, as well as a vertical support frame which hashandles for pushing the wheelchair and which supports the backrest. Ifthe seat shell is size-adjustable in a wide range, it makes sense toadjustably attach the vertical frame to the horizontal component. Forthis purpose, the chassis has preferably at least one receiver tube anda clamp body which is inserted into this receiver tube, the clamp bodybeing displaceable and lockable in a certain displacement area withinthis receiver tube. The clamp bodies are preferably attached tohorizontal braces which carry the frame extending vertically andtransversely to the longitudinal direction of the seat. In this way, theframe may be displaced in the longitudinal direction of the seat and maybe attached to the chassis in any position. Thus, the chassis may followthe size adjustment of the seat shell.

[0024] Embodiments of the present invention are described below withreference to the attached drawing.

[0025]FIG. 1 shows a side view of a seat shell according to the presentinvention on the chassis of a wheelchair;

[0026]FIG. 2 shows a side view of a part of an alternative connectingdevice connecting the backrest to the seat of the seat shell;

[0027]FIG. 3 shows a side view of the wheelchair of FIG. 1 with thebackrest and seat in the pivoted position;

[0028]FIG. 4 shows a side view of a part of a wheelchair correspondingto the embodiment of FIG. 1, having an alternative connecting device;

[0029]FIG. 5 shows a sectioned view of an extruded profile and aconnecting element along section line V-V of FIG. 1;

[0030]FIG. 6 shows a sectioned view of a double brace carrying thevertical frame of the chassis along section line VI-VI;

[0031]FIG. 7 shows a partially sectioned side view of the double braceof FIG. 6;

[0032]FIG. 8 shows a front view of pivoting lateral support pillowsattached to the seat;

[0033]FIG. 9 shows an enlarged view of a bracket for the support pillowsof FIG. 8;

[0034]FIG. 10 shows a side view of the support pillows of FIG. 8 with asectioned fastening device;

[0035]FIG. 11 shows a sectioned view of the support surface alongsection line XI-XI of FIG. 10.

[0036] The seat shell illustrated in FIG. 1 generally comprises abackrest 1, a seat 2, and a footrest 3. Backrest 1 and seat 2 are shownin FIG. 1 without the textile protecting case in which they are usuallyencased. Prior to use by a patient, the contact surfaces for body partsare provided with padding and encased with the protecting case. Thisensures a soft contact of the person sitting in the seat shell with thesurface of the seat shell. The padding and case are mostly omitted inthe figures for the sake of clarity.

[0037] Both backrest 1 and seat 2 have profiles 4 running on their twoside edges. These are aluminum extruded profiles 4, whose cross sectionis visible in particular in FIG. 5. FIG. 8 shows that a longitudinallyrunning profile 4 is attached to each side of seat 2. Backrest 1 alsohas a profile 4 on each of its sides.

[0038]FIGS. 5 and 9 show that profiles 4 have an essentially squarecross section. A groove 5 is located on each side of profile 4. Eachgroove 5 has lateral undercuts 6, so that either screw heads ordisplaceable sliding blocks may be inserted in groove 5 with a positivefit. Profile 4 has a longitudinal bore hole 7 in its center.

[0039]FIG. 1 shows the preferred embodiment in which seat 2 and backrest1 are pivotably linked to one another. A first base plate 12 is attachedto the side of backrest 1 in longitudinal groove 5 on profile 4 usingattachment screws 9. Screw head 10 (see FIG. 5) of attachment screw 9 isinserted in groove 5 with a positive fit. A cap nut 11 is threaded ontothe thread of attachment screw 9. In the same way, second base plate 8is attached to profile 4 on the side of seat 2.

[0040] Base plates 8 and 12 are pivotably connected using a pivot bolt13. On the other side of the seat arrangement, not shown in FIG. 1, asimilar connecting device is attached to profiles 4 of backrest 1 andseat 2 located there.

[0041] The bottom of seat 2 is held on chassis 15 of a wheelchairdisplaceably in the longitudinal direction of seat shell 2 by adisplaceable carriage 14; the chassis 15 has a large rear wheel 47 and asteerable front wheel 48 on either side. In addition, seat 2 ispivotably linked to carriage 14. Furthermore, pivotable holding elements16 are attached to the upper third of both side profiles 4 of backrest1; holding elements 16 link, pivotably about a pivot bolt 17, backrest 1to vertical frame 18 of chassis 15.

[0042] As FIG. 3 shows, in the event of an extending movement of aperson seated in the seat shell, backrest 1 pivots backward with respectto seat 2 and moves about pivot bolt 17 of holding element 16. Becausebackrest 1 is attached to vertical frame 18 of chassis 15 by holdingelement 16, seat 2 must be pushed forward and pivot upward, which ismade possible by carriage 14, to which seat 2 is pivotably articulated.

[0043] Pivot bolt 13, which permits backrest 1 to pivot with respect toseat 2, is located exactly at the height of the hip joint thanks to baseplates 8, 12 which are preferably used. In the case of a growing person,the position of pivot bolt 13 may be readjusted continuously, becauseattachment screws 9, which hold base plates 8, 12, are located inelongate holes 19, 20 of base plates 8, 12, elongate holes 19, 20extending transversely with respect to grooves 5 in profiles 4.

[0044] The same applies to footrest 3, which is supported by lateralbase plates 21, which are attached to both sides of seat 2 inlongitudinal groove 5. Lateral base plates 21 are connected to carryingelements 23 of footrest 3 via pivot bolt 22. Also in this case, theposition of pivot bolt 22 may be adjusted by displacing attachmentscrews 9 along groove 5 on the one hand and by displacing elongate holes24 through which attachment screws 9 pass on the other hand.

[0045]FIG. 4 shows an alternative embodiment of base plates 8′, 12′, and21′, in which a plurality of individual bore holes are situated in borehole rows 49 next to one another, instead of elongate holes. Thisembodiment also makes it possible to adjust the attachment of baseplates 8′, 12′, and 21′ to profiles 4 transversely to their grooves 5.Lateral support pillows 50 on backrest 1, visible in FIGS. 1 and 4, areknown as trunk pads, which support the upper body of the patient sittingin the wheelchair.

[0046]FIGS. 1 and 3 schematically show tension springs 25 and 26.Tension spring 25 draws carriage 14 backward, so that seat 2 isprestressed backward and backrest 1 is prestressed in the vertical,upright position. This prestressing force acts over the entire pivotingrange between backrest 1 and seat 2, as well as over the entiredisplacement path of seat 2. Tension spring 26 draws footrest 3 into theangled position with respect to seat 2, also over the entire pivotingrange of footrest 3.

[0047] Should the fastening device according to the present invention bedesigned to rigidly fastening a backrest 1 to a seat 2, a single rigidbase plate 27 may be attached to grooves 5 of profiles 4 on each side ofseat 2 via attachment screws 9 (see FIG. 2).

[0048] Fastening elements are also insertable into longitudinal boreholes 7 of profiles 4. For example, FIG. 1 shows that braces 28 for anadjustable holding device 29 for a head rest (not illustrated) ismounted on the upper section of longitudinal bore holes 7 of verticalprofiles 4 on backrest 1. One brace 28 is mounted on either side ofbackrest 1 in the profile mounted there.

[0049] An additional fastening element for an adjustable lateralsupporting element mounted in the longitudinal bore hole of profile 4 isdescribed below in connection with FIGS. 8 through 11.

[0050]FIGS. 6 and 7 first show the adjustability seen in FIG. 1 ofchassis 15 of the wheelchair. Vertical frame 18 is adjustable in size inthe longitudinal direction of seat 2. For this reason, vertical frame 18has, on its lower ends, two double braces 31 which are each insertablein a double tube 30 of chassis 15. Each brace of double brace 31 ishollow and, at its end, has a clamp body 32 resting on the oblique endof brace 31 via an oblique surface. Clamp bodies 32 may be drawn againstthe ends of double braces 31 using two draw spindles 33, so thatclamping occurs within double tube 30, and vertical frame 18 is securedon chassis 15. As mentioned previously, such double tubes 30 in which adouble brace 31 of vertical frame 18 is mounted are located on bothsides of seat 2.

[0051]FIGS. 8 through 11 show a novel fastening device for adjustablelateral support elements 34. Each support element 34 has a folded metalsheet 35, to which a pad 36 is attached. Each support element 34 isattached to a section 4 on one side of seat 2 using two brackets 37. Ascan be seen in FIG. 10 in particular, a connecting sleeve 38, obliquelyparted in the center, on whose two parts the two brackets 37 arenon-rotatably attached, extends in each section 4 within longitudinalbore hole 7 with little clearance. A threaded rod 40, whose threadedfront end is screwed into a clamp body 39, extends within connectingsleeve 38. The end of threaded rod 40 projecting outward carries a screwhead 41, which is positively engageable with a wrench. The screw head islocated on the front edge of seat 2 near footrest 3 (see FIG. 1). Clampbody 39 is displaced in the axial direction toward connecting sleeve 38by twisting threaded rod 40. It is also displaced radially outward overthe oblique surface of clamp body 39. Likewise, both connecting sleeves38 are displaced radially with respect to one another over their obliquesurfaces and are clamped within longitudinal bore hole 7 in section 4 onseat 2. After tightening threaded rod 40, brackets 37 are fastenedessentially rigidly to section 4.

[0052] Support element 34 may be locked to the upper end of brackets 37in a similar manner. As shown in FIG. 11, a draw spindle 42 is locatedwithin distance sleeves 43, 44. The front end of draw spindle 42 has ascrew head 45. When draw spindle 42 is tightened, folded areas 46 ofmetal sheet 35 are clamped into slits 47 within brackets 37. Both screwhead 45 of draw spindle 42 and screw head 41 of threaded rod 42 arelocated on the front end face of support element 34 and of section 4 onseat 2. Each support element 34 may thus be adjusted as desired both inits inclination and its position in the transverse direction of seat 2.

[0053] As FIG. 8 shows, support elements 34 may be adjusted to differentbody widths in a broad adjustment range. Pads 36 of support elements 34may also be set at an angle to one another, so that they enclose atrapezoidal space widening downward, for example. The support elements,which are also known as adduction guides, not only exert a lateralsupport force in this position, but also a holding force on the hip andlegs of the patient sitting in the wheelchair that prevents the patientfrom slipping out upward.

[0054] Extruded sections 4 are attached to backrest 1 and seat 2 in anysuitable manner. They may be directly welded onto metal plates formingbackrest 1 and seat 2, for example. A detachable joint, however, is alsopossible. FIG. 9 shows, for example, a threaded joint in which aconnecting screw 51 is screwed into an internal thread of a slidingblock 52, mounted in a longitudinal groove of section 4, through themetal plate forming seat 2. Such threaded joints may be situated atdifferent points along the length of section 4.

[0055] List of Reference Symbols

[0056]1 backrest

[0057]2 seat

[0058]3 footrest

[0059]4 section

[0060]5 groove

[0061]6 undercut

[0062]7 longitudinal bore hole

[0063]8 base plate

[0064]9 attachment screw

[0065]10 screw head

[0066]11 cap nut

[0067]12 base plate

[0068]13 pivot bolt

[0069]14 carriage

[0070]15 chassis

[0071]16 holding element

[0072]17 pivot bolt

[0073]18 vertical frame

[0074]19 elongate hole

[0075]20 elongate hole

[0076]21 base plate

[0077]22 pivot bolt

[0078]23 carrying element

[0079]24 elongate hole

[0080]25 tension spring

[0081]26 tension spring

[0082]27 rigid base plate

[0083]28 brace

[0084]29 holding device for head rest

[0085]30 double tube

[0086]31 double brace

[0087]32 clamp body

[0088]33 draw spindle

[0089]34 support element

[0090]35 metal sheet

[0091]36 pad

[0092]37 bracket

[0093]38 connecting sleeve

[0094]39 clamp body

[0095]40 threaded rod

[0096]41 screw head

[0097]42 draw spindle

[0098]43 distance sleeves

[0099]44 distance sleeves

[0100]45 screw head

[0101]46 folded area

[0102]47 rear wheel

[0103]48 front wheel

[0104]49 bore hole row

[0105]50 support pillow

[0106]51 connecting screw

[0107]52 sliding block

1. A seat shell which is provided in particular for attachment to thechassis (15) of a wheelchair or a stroller, having a backrest (1), aseat (2), and a footrest (3), characterized in that oblong recessesrunning in its longitudinal direction, grooves (5) in particular, forreceiving fastening elements are situated on both sides of the seat (2).2. The seat shell as recited in claim 1, characterized in that oblongrecesses running in its longitudinal direction, grooves (5) inparticular, for receiving fastening elements are situated on both sidesof the backrest (1).
 3. The seat shell as recited in claim 1 or claim 2,characterized in that a metallic extruded profile (4), having at leastone longitudinal groove (5), is attached to each side of the seat (2)and/or the backrest (1).
 4. The seat shell as recited in claim 3,characterized in that the extruded profile (4) has a rectangular crosssection and a continuous groove on all four sides.
 5. The seat shell asrecited in one of claims 2 through 4, characterized in that holdingelements (16), connecting the backrest (1) to the chassis (15), aremounted in the longitudinal grooves (5) of the backrest (1).
 6. The seatshell as recited in one of claims 3 through 5, characterized in that theextruded profiles (4) have a central longitudinal bore hole (7).
 7. Theseat shell as recited in claim 6, characterized in that the bore hole(7) serves the purpose of receiving fastening elements.
 8. The seatshell as recited in claim 7, characterized in that the fasteningelements support a headrest.
 9. The seat shell as recited in one of thepreceding claims, characterized in that lateral support elements (34)are adjustably attached to the seat (2), and the fastening elements(38-41) serve the purpose of locking the support elements (34) in theiradjusted position.
 10. The seat shell as recited in one of the precedingclaims, characterized in that joining elements (8, 12, 27), connectingthe backrest (1) to the seat (2), are mounted in the longitudinalgrooves (5) of the seat (2).
 11. The seat shell as recited in claim 10,characterized in that the joining elements (8, 12, 27) are mounted inthe longitudinal grooves (5) of the backrest (1).
 12. The seat shell asrecited in one of the preceding claims, characterized in that joiningelements (21), connecting the footrest (3) to the seat (2), are mountedin the longitudinal grooves (5) of the seat (2).
 13. The seat shell asrecited in one of claims 10 through 12, characterized in that thejoining elements (8, 12, 21) have an articulated design.
 14. The seatshell as recited in claim 13, characterized in that the joining elementsare composed of two base plates (8, 12) which are articulatedlyconnected to one another.
 15. The seat shell as recited in one of claims10 through 14, characterized in that the joining elements (8, 12, 21,27) are mounted in the longitudinal grooves (5) using attachment screws(9).
 16. The seat shell as recited in claim 15, characterized in thatthe joining elements (8, 12) have elongate holes (19, 20) for receivingthe attachment screws (9).
 17. The seat shell as recited in claim 1,characterized in that the chassis (15) to which the seat shell isattached has an adjustable design.
 18. The seat shell as recited inclaim 17, characterized in that the chassis (15) has at least onereceiver tube (30) and a clamp body (32) which is inserted into thisreceiver tube (30), the clamp body being lockable in a certaindisplacement area.
 19. The seat shell as recited in claim 18,characterized in that the clamp body (32) is attached to a frame (18)which extends vertically and transversally to the longitudinal directionof the seat (2).